The assumption is that, because Ivory took the Jags' money shortly before Forte became a Jet, Forte was replacing Ivory. I disagree.
I think Forte may be replacing Powell. As Elias said, Forte is much more like Powell than he is Ivory. And he's a better fit with Chan's system, considering how effective he is catching it out of the backfield.
What if the plan is to bring in Forte as a veteran speed back, and to look to the draft for a power back to replace Ivory? Of course, no rookie is going to be as effective as Ivory, but by drafting a power back as opposed to signing one, you are getting someone who has far lower mileage, far fewer hits. Let's say the Jets go with Forte, draft a guy like Jordan Howard out of Indiana in the third round, and see what the market bears for either Powell or another back?